One of coolest features of the Duo 280c is that you can display thousands of colours by reducing the display size from 640 x 480 to 640 x 400. One of the most annoying features of the Duo 280c is that you have to use the Options button in the Monitors control panel to do the switch. This requires many steps and is generally a pain. Worse yet, none of the standard depth switching tools are any help because they don’t deal with changing the size of the display in order to change the depth.
So I decided to write a quick hack to make this easier. The obvious place for such a quick hack is in the Control Strip.
DuoDepth is a control strip module that allows you to switch your Duo 280c from 640 x 480, 256 Colours or Greys, to 640 x 400, Thousands of Colours.
Installation and Use
You must have a Duo 280c to run DuoDepth. Install it by dragging it to the Control Strip Modules folder inside your system folder. You must restart for it to appear in your control strip.
Once you have rebooted you should see DuoDepth’s icon in the control strip. Clicking on it pops up a menu from which you can select the setting you want. The current setting is marked with a •.
Restrictions and Caveats
The primary restriction on DuoDepth is that it only works on a Duo 280c. The reason this restriction exists is that, in order to speed up its development, I made a lot of assumptions about the video setup and I’m very concerned that these assumptions will break on any other machines. I wait enthralled for an enterprising Duo 270c owner to hack out the check and inform me that it works on their hardware and I’ll add that machine to the list of supported machines.
Some of the assumptions I made are:
• That the built-in display in the main device, ie the device with the menu bar. God knows what happens if you move the menu bar to a NuBus card and try to switch modes on that display. Don’t do it!
• That, if the main device is less than 480 pixels high, the display is in 640 x 400 mode. This is only used to set the item in the menu and should only result in cosmetic problems if it fails.
• That the video modes 128 and 129 correspond to the thousands and 256 colour modes respectively.
I could fix all of these problems by using the Slot Manager to walk the Duo’s pseudo-declaration ROM and finding the data structures but I’m basically too lazy.
Oh yeah, DuoDepth scrambles your desktop icons totally when you switch the display size down. I’m not sure why this happens here but not with the Monitors control panel. If anyone has any idea how to stop this please let me know.
About the Source Code
The source code to DuoDepth is included in the archive. It compiles under MPW Pascal 3.3.1 with Universal Pascal Interfaces (UPI) 2.0. Apart from the restrictions noted above, I’m fairly happy with the source code. It is not at all skanky (–: Then again, it isn’t very large.
Credits
DuoDepth was developed by Quinn “The Eskimo!” with no help from anyone else (–: It was written on the afternoon of 7 July 1995. Version 1.0b1 is the first released version.
I don’t intend to do any more development on this beyond my own needs. If you are interested in taking over the development of this product — for example, to extend it to support different machines and remove some of the caveats — please contact me.
DuoDepth is Freeware and is dedicated to the Duo’s designers. Gods of Product Design we love you!
Quinn “The Eskimo!” <mailto:quinn@cs.uwa.edu.au> 7 July 1995
